In general, chillers that supply cold water to demand sources of cold water such as an air conditioner or a freezer include a compressor, a condenser, an expander, and an evaporator, through which a refrigerant circulates.
The evaporator in chillers is implemented by a liquid refrigerant heat exchanger to allow heat exchange between a refrigerant and water (hereafter, referred to as cold water), is connected with demand sources of cold water through a water pipe, and circulates and supplies cold water cooled by the refrigerant to the demand sources of cold water.
In the chillers, oil is discharged with the refrigerant when the compressor is driven, and flows into the evaporator and collects therein, after sequentially passing through the condenser and the expander together with the refrigerant.